One magnetron is sufficient. SiC apparently works.
https://www.youtube.com/watch?v=aoipiXvFAKQ <https://www.youtube.com/watch?v=aoipiXvFAKQ&html5=1> &html5=1 From: Axil Axil It is possible to build a custom microwave oven fed by two 1 kW, 2.45 GHz magnetrons to heat alumina up to 1300C.
